Electrically Conductive Elastic Composite Yarn

ABSTRACT

An electrically conductive elastic composite yarn comprises at least one elastic member having a ratio N being drafted length Ld over relaxed length Lr1 N being in the ränge of 1 to 10. The yarn further comprises more than one metal filament wrapped around the elastic member. The yarn is characterized in that each of the metal filaments is twisted with at least one other of the metal filaments.

BACKGROUND

The present invention relates to an electrically conductive elasticcomposite yarn, and a textile product comprising such yarn. Theinvention further relates to the use of such textile products.

Metal fibers and especially metal filaments are known as elements of anelectrically conductive yarn. As an example, an electrically conductiveyarn is used as a thermal fuse in U.S. Pat. No. 5,927,060, or forevacuation of electrostatic charges build up in a textile fabric such asdescribed in U.S. Pat. No. 3,288,175.

Electrically conductive elastic composite yarns are known fromWO2004/097089. This document, upon which the preamble of the presentfirst claim is based, describes electrically conductive elasticcomposite yarns comprising at least one elastic member having a ratio N,this is the drafted length Ld over relaxed length Lr of this elasticmember, being in the range of 1 to 8. This yarn may comprise more thanone metal filament wrapped around the elastic member. The metalfilaments have a length which is at least equal to the drafted length ofthe elastic member. The yarn has the advantage that, when beingsubjected to elongation, the metal filaments are not subjected totensile stress.

The yarn may however suffer from some disadvantages. Because of the verylarge length of metal filaments in the yarn per linear meter of yarn,the metal filaments are very likely not to be in contact with the outersurface of the elastic member. Because of this, the metal filament hasthe liberty to displace randomly around the elastic member when thelatter is not under tension. When this yarn is used to provide a textileproduct, some metal filament loops may tend to stick out of the textileproduct due to random deformation of the metal filaments. Thisphenomenon usually occurs when the textile product was stretchedrepetitively.

This freedom of movement of the metal filaments may as well cause someminor changes in electrical properties of the yarn, because after eachstretching of the textile, in casu the yarn, there may occur a differentnumber of contacting points between adjacent loops of the same filament,or between several filaments used to provide the same yarn.

The fact that metal filaments may lose contact with the underlyingelastic member, may as well cause more frequent filament ruptures, ormay disturb the production of the textile fabric in which the yarn isused, or may disturb the use of the textile product because of filamentspointing out of the surface of the textile product.

The fact that the metal filaments are making contact with the underlyingelastic member, may increase drastically the so-called flexlife of theelectrically conductive elastic composite yarn.

SUMMARY

Particular and preferred aspects of the invention are set out in theaccompanying independent and dependent claims. Combinations of featuresfrom the dependent claims may be combined with features of theindependent claims as appropriate and not merely as explicitly set outin the claims.

An aspect of the claimed invention provides an electrically conductiveelastic composite yarn. An aspect of the present invention provides anelectrically conductive elastic composite yarn which has stableelectrical conductive properties over life time when repetitivelystretched to a large extent. An aspect of the present invention providesan electrically conductive elastic composite yarn which can berepetitively stretched to a large extent, meanwhile not having metalfilaments buckling out of the yarn or the textile product in which it isused. Another aspect of the present invention provides an electricallyconductive elastic composite yarn of which the electrical resistance iseasy to calculate. Another aspect of the present invention provides anelectrically conductive elastic composite yarn which is easy to use forproviding textile products such as woven, braided or knitted textileproducts, and garments comprising such textile products comprising anelectrically conductive elastic composite yarn as subject of theinvention.

A further aspect of the present invention provides a textile productcomprising an electrically conductive elastic composite yarn, and agarment comprising a textile product comprising an electricallyconductive elastic composite yarn.

A further aspect of the present invention provides a textile product anda garment, which has been incorporated in this product or garment, anelectrically conductive elastic composite yarn serving as an operationalsafe antenna or resistive heating element, having stable and predictableelectrical properties and a very high so-called flexlife.

An embodiment of the invention provides an electrically conductiveelastic composite yarn having the features as set out in thecharacterizing portion of present claim 1. Use of such electricallyconductive elastic composite yarn provides a textile product and/or agarment, wherein such electrically conductive elastic composite yarn isused e.g. as an antenna. Advantageous embodiments are set out in thedependent claims.

Surprisingly, it was found that the fact that for each metal filament inthe yarn, the metal filaments being twisted with at least one othermetal filament reduces the risk on metal filaments displacing relativelyfreely during cycles of stretching and relaxing the yarn. Within theyarn substantially all of an elongating stress imposed on the compositeyarn is carried by the elastic member. This is because the conductivecovering filaments have a length that is at least equal to the draftedlength of the elastic member. All of this results in electricalproperties of the electrically conductive elastic composite yarn whichare predictable at the start, and remain unchanged during repetitivestretching and relaxing cycles of the yarn. As the number of contactingpoints between the twisted filaments remain unchanged during stretching,and as, in case of more than two groups of twisted filaments being woundaround the same elastic member, preferably in opposite direction, thenumber of contacting points between the groups of filaments remainunchanged during stretching and no significant deviation of electricalproperties of the yarn is noticed.

The twisted filaments, or alternatively more than one group of twistedfilaments, are wrapped around an elastic member.

The drafted length Ld of the elastic member is defined to be that lengthto which the elastic member may be stretched and return to within fivepercent (5%) of its relaxed (stress free) unit length L.

The ratio N of the elastic member is defined as drafted length Ld overrelaxed length Lr. For yarns as subject of the invention, N is in therange of 1 to 10, more preferably in the range 1.5 to 5, or even morepreferred in the range 1.5 to 3.

Preferably this elastic member is provided out of elastic polymer ornatural or artificial rubber. As an example, polyurethane may be used.The elastic member may e.g. comprise only one elastic filament, or maycomprise a number of elastic filaments, possibly twined to each other.

The filaments are metal filaments preferably having an equivalentdiameter D being equal or more than 1 μm, and less or equal to 150 μm.More preferred, the equivalent diameter ranges from 6 μm to 65 μm

The metal filaments used to provide a yarn as subject of the inventionpreferably comprises copper or copper-alloy, nickel or nickel-alloy,aluminium or aluminium-alloy, silver or silver alloy or steel such asstainless steel. Possibly each filament is provided out of a core metal,encompassed by one or more metal layers. As an example each filament maycomprise a steel core such as a low carbon steel core being providedwith a layer of an other metal, preferably a metal being moreelectrically conductive than the core, such as a copper-layer or acopper-alloy layer, an aluminium layer or an aluminium-alloy layer, asilver or a silver-alloy layer, a tin or a tin alloy layer. The layer ispreferably provided by cladding. One can also provide an outer layerwhich leads to an improved resistance to galvanic corrosion because ofe.g. sweat or salt liquids, such as a metal layer comprising nickel or anickel-alloy, titan or a titan-alloy, silver or a silver-alloy or suchas a polymer layer.

Most preferred, the metal filaments are provided by a metal fiber bundledrawing operation. The metal filaments, which obtain in that case asubstantially polygonal, usually penta- or hexagonal cross section, arecharacterized by an equivalent diameter, which is the diameter of animaginary circle, having the same surface area as the average surfacearea of a radial cross section of the metal filament.

According to the present invention, each of the metal filaments istwined with at least one other of the metal filaments of the yarn assubject of the invention. The total number of filaments used to providea yarn as subject of the invention is preferably in the range of 2 to1000.

Possibly the metal filaments of the yarn as subject of the inventioncould be grouped in at least two groups of metal filaments, which metalfilaments of each of said groups are twisted with each other. It wasfound that preferably each of said groups comprises M metal filaments,for which M being at least 2 and preferably less or equal than 550. Morepreferred, M ranging from 2 to 280 such as 2, 9, 10, 50, 125 or 275.

As at least 2 and preferably more than 2 metal filaments are used, whichare twisted to each other, the yarn, when subjected to a stretchingoperation, is less vulnerable to filament ruptures, because of thetwisting of the filaments. The tension which may be imposed on the metalfilaments, are not to be born by only one metal filament, but aresubstantially equally divided amongst all the filaments present. Anadditional advantage is that, in case one filament is broken, theelectrical properties of the yarn itself is few or not influenced due tothe numerous contacts between the filaments being twisted together, andbetween the different groups of filaments in case such different groupsare present. It was found that the electrical properties of the yarn arenot influenced as long as not more than 80% of the filaments are broken.

It was found that for each representative section of the yarn as subjectof the invention having a relaxed length S, preferably the shortestmetal filament in this section has a length F for which F being largeror equal to S, and F being smaller or equal to 5*S, more preferredsmaller than 3.5*S.

Further it was found that for each representative section of the yarn assubject of the invention having a relaxed length S, preferably thelength of each of the metal filaments in this section is smaller orequal to 3*S.

Each of the metal filaments is twisted with at least one other metalfilament. Preferably a number of turns per meter between 10 and 200 isused.

Possibly at least two groups of metal filaments, which filaments aretwisted with each other, are used to provide a yarn as subject of theinvention. It was found that when at least two groups of metal filamentsare present, the number of contacting points between the groups offilaments remain unchanged during stretching, resulting in nosignificant deviation of electrical properties of the yarn. This wasespecially the case when at least one group is wrapped around theelastic member in a first direction, whereas at least one of the othergroups of metal fibers is wrapped in the opposite direction around theelastic member. This also contributes to a reduction of the livelinessof the yarn as subject of the invention. Possibly the groups of metalfilaments are provided around the elastic member by braiding, which isalso to be understood as wrapping in the spirit of the presentinvention.

In order to further reduce the liveliness of the yarn as subject of theinvention, so providing a yarn which is more suitable and easy toprocess in textile production processes such as braiding, weaving orknitting, preferably the direction of twisting is opposite to thedirection used to wrap the group of fibers around the elastic element.

Most preferred, the number of groups of filaments being wrapped in ondirection around the elastic member, say the S-direction, is equal tothe number of groups of filaments being wrapped in the opposite, say theZ-direction around the elastic member.

Possibly a group of metal filaments comprises two or more subsets, eachsubset comprising at least two metal filaments being twisted with eachother. The subsets are then twined with each other in order to providethe group of metal filaments, which on its turn is wrapped around theelastic member.

The number of turns per linear meter of relaxed yarn of the filamentswrapped around the elastic member, or in case of more than one group ofmetal filaments, the number of turns per linear meter of relaxed yarn ofeach of the groups wrapped around the elastic member is preferablybetween 150 and 1400. The numbers or turns per linear meter of yarn maybe equal for each of the groups of metal filaments in case the yarncomprises more than one group of metal filaments.

According to the present invention, the electrically conductive elasticcomposite yarn as subject of the invention may be used to provide atextile product, e.g. a braided, woven or knitted textile product. Theelectrically conductive elastic composite yarn has the advantage thatthere are few or no metal filaments pointing out of the yarn, whichenabled a smooth and trouble free incorporation of the yarn in thetextile product.

Preferably, the electrically conductive elastic composite yarn is usedto provide an elastic tape like woven fabric, in which the electricallyconductive elastic composite yarn is present as a warp element.Possibly, the woven tape is woven so-to-say around the electricallyconductive elastic composite yarn, which are present as non interwovenwarp elements in a pocket. The other warp elements may comprise elasticyarns as well.

A tape-like woven structure with incorporated electrically conductiveelastic composite yarns as subject of the invention may so be obtained.It was found that such tapes, when subjected to repetitive elongation,has no tendency to show metal filaments sticking out of the surface ofthe woven textile product.

A similar property was found for braided and knitted textile products.

The textile product as subject of the invention may have an elongationat rupture in the range of 100% to 400%, more preferred in the range of200% to 350%. This elongation is measured by subjecting a textile samplewith a given length to an elongation until rupture of one of the yarnscomprised in the fabric. The length at rupture divided by the length ofthe textile fabric prior to elongation, and expressed in percentages isunderstood as the above-mentioned elongation at rupture.

It was found that the textile product may be used to provide a garment,wherein the electrically conductive elastic composite yarn, incorporatedin the textile product, is used as e.g. an antenna. It was found thatpreferably a electrically conductive elastic composite yarn, beingpresent in a loop shape in the garment, may function very well as a loopantenna. Especially tape-like woven textile products are suitable forsuch use. By integrating the electrically conductive elastic compositeyarn into a woven tape and by connecting the two ends of the yarn, bymeans of e.g. electrical conductive snap fasteners, this tape could workas loop antenna when worn around e.g. the body of a person.

Alternatively, the textile product comprising an electrically conductiveelastic composite yarn as subject of the invention may function as aheatable textile product, wherein the electrically conductive elasticcomposite yarn functions as a resistive heating element. For theintended applications, the textile product may be part of a garment.Especially garments being seat upholstery, e.g. car seat upholstery,benefits from the stable and reliable electrical properties of the yarnas subject of the invention under any stretched condition. Further itwas noticed that the so-called flex-life of the resistive element wassignificantly improved. Flex-life is to be understood as the resistanceto rupture of the yarn under repetitive bending conditions. As analternative, the textile product or the yarn as subject of the inventionitself may be part of a heating device which is integrated in the carseat as such, usually between the foamed part of the seat and theupholstery.

As further alternative used, the yarn as subject of the invention or atextile product as subject of the invention may be used as part of anelectrode for detection and/or measuring the presence of body liquidssuch as sweat or urine, or as a part of a sensor for measuring anddetecting hart beat or respiration monitoring.

As further alternative, the yarn as subject of the invention or atextile product as subject of the invention may be used as leadwirewhich connects different electronic devices to each other such asbatteries, PCB's, monitoring devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described hereinafter, by way of example only,with reference to the accompanying drawings wherein

FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5 show schematically a yarn inaccordance with examples of the invention;

FIG. 6 shows schematically a tape-like woven structure in accordancewith an example of the invention;

FIG. 7 shows schematically a garment comprising a textile product inaccordance with an example of the invention;

FIG. 8 shows schematically a car seat comprising a textile product inaccordance with an example of the invention as resistance heatingelement.

DESCRIPTION OF THE PARTICULAR EMBODIMENTS

FIG. 1 shows schematically a yarn 101 in accordance with an example ofthe invention, which yarn comprises an elastic member 110, which iswrapped with mutually twisted metal filaments, together indicated 120.As an example, elastic member 110 is a natural rubber filament, whereasthe metal filaments 120 comprise 275 filaments of alloy stainless steelAISI 316L, and having an equivalent diameter of 12 μm. They are twistedto each other using 100 turns per meter in Z direction, and subsequentlyare wrapped in S direction around the elastic member 110 using 1100turns per meter.

The ratio N of drafted length Ld over relaxed length Lr of the elasticmember is 1,4. For a relaxed length S being 100 mm of the yarn 101, thelength of each of the filaments is substantially equal, thus is the sameas the shortest length F of a metal filament. In this embodiment F is140 mm.

The electrical resistance of this yarn 101 is 21 ohm/meter.

Alternatively, the metal filaments 120 comprise 90 filaments of alloystainless steel AISI 316L, and having an equivalent diameter of 14 μm.They are twisted with each other using 100 turns per meter in Zdirection, and subsequently are wrapped in S direction around theelastic member 110 using 1000 turns per meter.

An alternative yarn 201 in accordance with an example of the inventionis shown schematically in FIG. 2. The yarn 201 comprises an elasticmember 210, which is wrapped with two groups 221 and 222 of mutuallytwisted metal filaments. As an example, elastic member 210 is naturalrubber filament, whereas each of the groups 221 and 222 of metalfilaments comprises 550 filaments of alloy 316L having an equivalentdiameter of 12 μm. The first group 221 is twisted to each other using175 turn per meter in S direction, and subsequently is wrapped in Zdirection around the elastic member 210 using 1000 turns per meter. Thesecond group 222 is twisted to each other using 175 turns per meter in Zdirection, and subsequently is wrapped in S direction around the elasticmember 210 using 1000 turns per meter.

The ratio N of drafted length Ld over relaxed length Lr of the elasticmember 210 is 1,4. For a relaxed length S of 100 mm of the yarn 201, thelength of each of the filaments either from the first group 221 orsecond group 222 is substantially equal, thus is the same as theshortest length F of a metal filament. In this case, F is 140 mm.

The electrical resistance of this yarn 201 is 10 ohm/meter.

An alternative yarn 301 in accordance with an example of the inventionis shown schematically in FIG. 3. The yarn 301 comprises an elasticmember 310, which is wrapped with eight groups 321, 322, 323, 324, 325,326, 327 and 328 of mutually twisted metal filaments. As an example,elastic member 310 is natural rubber filament, whereas each of thegroups 321, 322, 323, 324, 325, 326, 327 and 328 of metal filamentscomprises 550 filaments of alloy AISI 316L, and having an equivalentdiameter of 12 μm. The groups 221, 323, 325 and 327 are twisted to eachother using 175 turns per meter in S direction. The groups 322, 324, 326and 328 are twisted to each other using 175 turns per meter in Zdirection. The eight groups are then braided around the elastic member310 in such a way that the groups 321, 323, 325 and 327 followsubstantially a path as if they would be wrapped in Z direction aroundthe elastic member 310. The groups 322, 324, 326 and 328 followsubstantially a path as if they would be wrapped in S direction aroundthe elastic member 310. All groups 321, 322, 323, 324, 325, 326, 327 and328 make 1000 turns per meter of yarn.

The ratio N of drafted length Ld over relaxed length Lr of the elasticmember 310 is 1,5. For a relaxed length S of 100 mm of the yarn 301, thelength of each of the filaments either from the groups 321, 322, 323,324, 325, 326, 327 and 328 is substantially equal thus is the same asthe shortest length F of a metal filament. In this case, F is 150 mm.The electrical resistance of this yarn 301 is 5 ohm/meter.

An alternative yarn 401 in accordance with an example of the inventionis shown schematically in FIG. 4. The yarn 401 comprises an elasticmember 410, which is wrapped with two groups 421 and 422 of mutuallytwisted metal filaments. The elastic member 410 comprises more than one,e.g. three elastic monofilaments 411, 412 and 413, being natural rubberfilaments, whereas each of the groups 421 and 422 of metal filamentscomprises 180 filaments of alloy 316L having an equivalent diameter of14 μm. The first group 421 is twisted around each other using 100 turnsper meter in S direction, and subsequently is wrapped in Z directionaround the elastic member 410 using 1000 turn per meter. The secondgroup 422 is twisted around each other using 175 turns per meter in Zdirection, and subsequently is wrapped in S direction around the elasticmember 410 using 1100 turns per meter.

The ratio N of drafted length Ld over relaxed length Lr of the elasticmember 410 is 1,5. For a relaxed length S of 100 mm of the yarn 401, thelength of each of the filaments either from the first group 421 orsecond group 422 is substantially equal thus is the same as the shortestlength F of a metal filament. F is 150 mm.

The electrical resistance of this yarn 401 is 22 ohm/meter.

An alternative yarn 501 in accordance with an example of the inventionis shown schematically in FIG. 5. The yarn 501 comprises an elasticmember 510, which is wrapped with two groups 521 and 522 of mutuallytwisted metal filaments. The elastic member 510 comprises more than one,e.g. three elastic monofilaments 511, 512 and 513, being provided out ofnatural rubber, whereas each of the groups 521 and 522 of metalfilaments comprises 7 filaments of copper clad steel, and having anequivalent diameter of 63 μm. The first group 521 is twisted to eachother using 60 turns per meter in Z direction, and is wrapped in Zdirection around the elastic member 510 using 850 turns per meter. Thesecond group 522 is twisted to each other using 60 turns per meter in Zdirection, and is wrapped in S direction around the elastic member 510using 700 turns per meter.

The ratio N of drafted length Ld over relaxed length Lr of the elasticmember 510 is 3,0. For a relaxed length S of 100 mm of the yarn 501, thelength of each of the filaments from the first group is the shortestlength F of a metal filament, being 300 mm.

The electrical resistance of this yarn 501 is 5 ohm/meter.

Each of the above mentioned yarns in accordance with the examples of theinvention may be used to provide a textile product. Such a textileproduct may, as an example, be a woven textile product 601 asschematically shown in FIG. 6.

The woven fabric 601 has a warp direction 610 and a weft direction 611.A number of elastic electrically conductive yarns 620 in accordance withan example of the invention are present as elements in warp direction610. The woven fabric has substantially three zones, being two sidezones 630 and 631, between which a pocket-like zone 640 is located. Theyarns 620 are provided in the interior of the pocket-like zone. In orderto make electrical contact with an electronic device with which thewoven textile product is to be connected, two snap fasteners 650 areprovided, preferably in stainless steel.

The elongation at rupture of the textile woven product is 310%

FIG. 7 shows schematically a garment comprising a textile product inaccordance with an example of the invention.

The garment, either e.g. a vest or as shown in FIG. 7, a shirt 701, maycomprise one or more textile products 711, 712, 713, 714 in accordancewith examples of the invention for serving multiple purposes such assweat detection, heart beat detection or monitoring, blood pressuremeasurement, or any other known application of electrically conductivetextiles in garments. The textile products 711, 712, 713, 714 may serveas well as an antenna for receiving or sending EM-waves. Preferably inthis case, the textile products 711, 712, 713 are used as they areprovided in the shape of a loop antenna, since both ends of the tape,and both ends of the yarn in accordance with an example of the inventionare approaching each other in such a way that the yarn or yarns arepresent according to a loop-shape. Preferably the textile products 711,712, 713, 714 are similar to the tape like woven fabric 601 as shown inFIG. 6. The electronic device such as a transducer or receiver, iscoupled to the two snap fasteners 650.

Alike, the garment being pants 702 may comprise a textile product 721 inaccordance with an example of the invention comprising yarns inaccordance with an example of the invention. Preferably the textileproduct 721 is similar to the tape like woven fabric 601 as shown inFIG. 6. The textile product 721 may serve as well as a loop antenna forreceiving or sending EM-waves. The electronic device such as atransducer or receiver, is coupled to the two snap fasteners 650, and inthis case may easily be carried in the pocket 722 by the person wearingthe pants. The snap fastener or alike coupling element may extend fromthe textile product 721 to the inner side of the pocket.

As an other alternative, the garment being a belt 703, may comprise atextile product 731 in accordance with an example of the inventioncomprising yarns in accordance with an example of the invention. Also inthis case, the textile product 731 may be used as a loop antenna.

Another use is shown in FIG. 8. A car seat 801 may be provided with atextile product 810 in accordance with an example of the invention,comprising yarns in accordance with an example of the invention servingas electrically heating yarns 812 by means of resistance heating. Theyarns 812 in accordance with an example of the invention may be coupledto an electrical device providing the necessary current for use in theheatable textile, by means of two cables 813, each being coupled to anelectrode 811 to which the yarns 812 are coupled. The electrodes 811itself may as well comprise yarn in accordance with an example of theinvention, being it with a smaller electrical resistance as the yarns812.

The textile product 810 may be provided as a device being locatedbetween the foamed part 820 of the seat, or as an integrated part of theupholstery of the car seat.

An aspect of the invention can provide an electrically conductiveelastic composite yarn which comprises at least one elastic memberhaving a ratio N being drafted length Ld over relaxed length Lr, N beingin the range of 1 to 10. The yarn further comprises more than one metalfilament wrapped around the elastic member. The yarn is characterized inthat each of the metal filaments is twisted with at least one other ofthe metal filaments.

1. An electrically conductive elastic composite yarn comprising at leastone elastic member having a ratio N being drafted length Ld over relaxedlength Lr, said N being in the range of 1 to 10, said yarn furthercomprising more than one metal filament wrapped around said at least oneelastic member, said metal filament having a length that is equal to orgreater than the drafted length Ld, characterized in that each of saidmetal filaments is twisted with at least one other of said filaments. 2.An electrically conductive elastic composite yarn as in claim 1, whereinsaid metal filaments are wrapped around said at least one elastic memberusing a number of turns per meter of said yarn in the range of 150 turnsper meter to 1400 turns per meter.
 3. An electrically conductive elasticcomposite yarn as in claim 1, wherein said metal filaments are twistedin a direction of twist, said filaments are wrapped around said at leastone elastic element in the opposite direction of said direction oftwist.
 4. An electrically conductive elastic composite yarn as in claim1, wherein said yarn comprising at least a first group of metalfilaments being twisted with each other and a second group of metalfilaments being twisted with each other, said first group and saidsecond group being wrapped around said at least one elastic member. 5.An electrically conductive elastic composite yarn as in claim 1, whereinsaid yarn comprising more than 2 groups of metal filaments being twistedwith each other.
 6. An electrically conductive elastic composite yarn asin claim 4, wherein said first group is wrapped around said at least oneelastic element in S-direction, said second group being wrapped aroundsaid at least one elastic member in Z-direction.
 7. An electricallyconductive elastic composite yarn as in claim 4, wherein the number ofgroups being wrapped around said at least one elastic member inS-direction is equal to number of groups being wrapped around said atleast one elastic member in Z-direction.
 8. An electrically conductiveelastic composite yarn as in claim 4, wherein each of said groupscomprises a number of metal filaments M, said M being equal or more than2, said M being less or equal to 550
 9. An electrically conductiveelastic composite yarn as in claim 8, wherein said M is identical numberfor each of said groups of metal filaments.
 10. An electricallyconductive elastic composite yarn as in claim 1, wherein said yarncomprises 1000 or less metal filaments.
 11. An electrically conductiveelastic composite yarn as in claim 1, wherein each of said metalfilaments are twisted with at least one other of said filaments usingbetween 10 and 200 turns per meter.
 12. An electrically conductiveelastic composite yarn as in claim 1, wherein for each section of theyarn having a relaxed length S, the shortest of said metal filaments insaid section having a length F, said F being equal or larger than S,said F being less or equal than 5*S.
 13. An electrically conductiveelastic composite yarn as in claim 1, wherein for each section of theyarn having a relaxed length S, the length of each of said metalfilaments is less or equal than 3*S.
 14. An electrically conductiveelastic composite yarn as in claim 1, wherein said N being in the rangeof 1.5 to
 5. 15. An electrically conductive elastic composite yarn as inclaim 1, wherein said at least one elastic element being a polyurethanemember of a natural or artificial rubber member.
 16. An electricallyconductive elastic composite yarn as in claim 1, wherein each of saidmetal filaments have an equivalent diameter D, said D being equal ormore than 1 μm, said D being less or equal to 150 μm.
 17. Anelectrically conductive elastic composite yarn as in claim 1, whereineach of said metal filaments is provided by metal fiber bundle drawingoperation.
 18. An electrically conductive elastic composite yarn as inclaim 1, wherein each of said metal filaments comprises copper orcopper-alloy, steel, nickel or nickel-alloy, aluminium oraluminium-alloy or stainless steel.
 19. A textile product comprising atleast one electrically conductive elastic composite yarn as in claim 1.20. A textile product as in claim 19, wherein said textile product is awoven fabric.
 21. A textile product as in claim 20, wherein said yarn ispresent as a weft or warp yarn.
 22. A textile product as in claim 19,wherein said textile product having an elongation at rupture of 100% to400%.
 23. A garment comprising a textile product as in claim
 19. 24. Agarment as in claim 23, wherein said yarn is present as a loop.
 25. Agarment as in claim 23, wherein said garment being a seat upholstery.26. An electrically heating device comprising at least one electricallyconductive elastic composite yarn as in claim
 1. 27. An electricallyheating device comprising a textile product as in claim
 19. 28. The useof an electrically conductive elastic composite yarn as in claim 1 as anantenna.
 29. The use of an electrically conductive elastic compositeyarn as in claim 1 as a resistive heating element.
 30. The use of atextile product as in claim 19, wherein said yarn being used as anantenna.
 31. The use of a textile product as in claim 30, wherein saidyarn being present as a loop-antenna.
 32. The use of a textile productas in claim 19, wherein said yarn being used as a resistive heatingelement.
 33. The use of a garment as in claim 23, wherein said yarnbeing used as an antenna.
 34. The use of a garment as in claim 33,wherein said yarn being present as a loop-antenna.
 35. The use of agarment as in claim 23, wherein said yarn being used as a resistiveheating element.
 36. The use of a garment as in claim 33, wherein saidgarment being a seat upholstery.